Machine tools such as internal and external grinding machines are known to utilize workpart centering mechanisms for positioning a workpart relative to a workpart chuck that rotates the workpart for grinding operations. In production type of machining operations, magnetic faceplate chucking is less frequently used since time is lost and skilled operator attention is required for centering each workpiece on the faceplate. A dial indicator and skillfully dealt hammer blows to the workpiece are required to center the workpiece. Of course, the object for the operator is to center the workpiece on the faceplate with the geometrical axis of the workpiece substantially coaxial with the rotational axis of the faceplate that is attached on a rotatable spindle.
Automatic centering control mechanisms using a single drive shoe to center the workpart have been developed. However, such systems cannot be employed in traditional centerless tooling procedures in which the workpart axis is intentionally offset from the spindle axis for the grinding operation. A need exists for a workpart chuck centering mechanism that can be adapted for centerless tooling procedures yet provides a system employing computer numerically controlled capabilities for automated centering.